Less than a month after a dead NASA satellite came crashing to Earth, the sky is falling again. The defunct 2.7-ton German ROSAT satellite is slated to make a fiery, uncontrolled re-entry to our atmosphere sometime Saturday or Sunday (Oct. 22 or 23). Experts say the broken-up bits of ROSAT have a roughly 1-in-2,000 chance of hitting someone somewhere on Earth. That risk, while still quite remote, is higher than the 1-in-3,200 chance posed by NASA's UARS satellite, which fell uneventfully into the Pacific Ocean on Sept. 24.